Measurement of resin pressure in composite laminates during cure

• Main Author: Mackenzie, Katherine A.
• Language: English
• Published: 2008
• Online Access: http://hdl.handle.net/2429/2456

A promising method of measuring the resin pressure within a composite laminate during processing has been developed. This method can be used to investigate the control of voids, or resin flow and laminate compaction in several composite material processing methods such as ACND, hot press curing and resin transfer moulding. Sensor assemblies were developed and tested to show that their response is reproducible, linear and stable with temperature and time. Resin pressure profiles for three AS4/3501-6 laminates were generated and compared. The experimental results were compared to a resin flow model simulation. The prepreg used for the experiments was aged, so the simulation was run several times with various initial degrees of cure of the resin. Experimental data were compared to the simulation predictions to determine the apparent initial degree of cure of the resin, and the resin pressure profiles from the experiments and the simulation with this resin initial degree of cure were compared. The resin pressure within a laminate increases with the applied pressure until flow begins, at which time the resin pressure drops off progressively through the laminate thickness from the top surface to the tool plate. Conversely, the pressure at the surface of the laminate, next to the bleeder, remains at the vacuum pressure until the onset of flow when it increases as resin enters the bleeder. The measured resin pressure profiles were consistent both with the experimental results, and the simulation predictions. An advanced degree of cure of the resin at the start of the cure cycle significantly affects the resin flow and compaction in a laminate during cure.